The present invention relates to wireless communication, and more particularly, to a wireless communication method supporting a reverse report and a related wireless communication system.
IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specifications for implementing wireless local area network (WLAN) computer communication in the 2.4, 3.6, 5, and 60 GHz frequency bands, which are created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802). The base version of the standard was released in 1997; since then, there have been some amendments. The original standard together with subsequent amendments provides the basis for wireless network products using the Wi-Fi brand. While each amendment is officially revoked when it is incorporated into the latest version of the standard, the corporate world tends to market to the revisions as these concisely denote capabilities of their products. As a result, in the market place, each revision tends to become its own standard.
In the 802.11v and 802.11mc standards, a scheme for calculating clock offset or time of flight between two stations in order to derive the distance between the two stations according to “spec 802.11 2012 FIG. 10-23” is introduced.
FIG. 1 is a diagram illustrating the communicating progress of a conventional wireless communication system. The wireless communication system 100 comprises an initiator 101 and a responder 102. Conventionally, the initiator 101 may be a phone station, and the responder 102 may be an access point. In order to calculate the time of flight, the initiator 101 sends a request frame RF1 to the responder 102 to notify the responder 102 and receives an acknowledgement ACKrf1 from the responder 102. Next, the responder 102 sends a measurement frame MF11 at a departure time t1 which arrives at the initiator 101 at an arrival time t2, and an acknowledgement ACK11 is sent from the initiator 101 at a departure time t3 which arrives at the responder 102 at an arrival time t4. The responder 102 sends a measurement frame MF12 which comprises the information about the departure time t1 of the measurement frame MF1 and the arrival time t4 of the acknowledgement ACK1 to the initiator 101 for further processing. An acknowledgement ACK12 corresponding to the measurement frame MF12 is then sent to the responder 102 from the initiator 101.
It should be observed that the conventional wireless communication method is a unidirectional handshake to obtain all required timing parameters for clock offset, timing synchronization or round-trip time calculation, which consumes more power if the responder 102 has to re-initiate one more handshake to obtain information from the initiator 101. For example, in a peer-to-peer scenario such as gaming/social network, the initiator 101 requests timing measurement handshake for ranging while the responder 102 would like to acquire the distance to the initiator. In another example, for a commercial network such as a mall, the initiator 101 requests timing measurement handshake for location while the responder 102 would like to collect the distance of the initiator 101 to a server for location-based service.